diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index 5aced5e81f..178073822b 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -114,6 +114,9 @@ Trunk (unreleased changes)
 
     HDFS-3695. Genericize format() to non-file JournalManagers. (todd)
 
+    HDFS-3789. JournalManager#format() should be able to throw IOException
+    (Ivan Kelly via todd)
+
   OPTIMIZATIONS
 
   BUG FIXES
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/contrib/bkjournal/src/main/java/org/apache/hadoop/contrib/bkjournal/BookKeeperJournalManager.java b/hadoop-hdfs-project/hadoop-hdfs/src/contrib/bkjournal/src/main/java/org/apache/hadoop/contrib/bkjournal/BookKeeperJournalManager.java
index 8636fb7246..380db25703 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/contrib/bkjournal/src/main/java/org/apache/hadoop/contrib/bkjournal/BookKeeperJournalManager.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/contrib/bkjournal/src/main/java/org/apache/hadoop/contrib/bkjournal/BookKeeperJournalManager.java
@@ -272,7 +272,7 @@ public void processResult(int rc, String path, Object ctx, String name) {
   }
 
   @Override
-  public void format(NamespaceInfo ns) {
+  public void format(NamespaceInfo ns) throws IOException {
     // Currently, BKJM automatically formats itself when first accessed.
     // TODO: change over to explicit formatting so that the admin can
     // clear out the BK storage when reformatting a cluster.
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FileJournalManager.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FileJournalManager.java
index 64bc607c32..d9acff9944 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FileJournalManager.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FileJournalManager.java
@@ -79,7 +79,7 @@ public FileJournalManager(StorageDirectory sd,
   public void close() throws IOException {}
   
   @Override
-  public void format(NamespaceInfo ns) {
+  public void format(NamespaceInfo ns) throws IOException {
     // Formatting file journals is done by the StorageDirectory
     // format code, since they may share their directory with
     // checkpoints, etc.
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/JournalManager.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/JournalManager.java
index 6fe5aad4ea..c95cb206ce 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/JournalManager.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/JournalManager.java
@@ -41,7 +41,7 @@ public interface JournalManager extends Closeable, FormatConfirmable {
    * Format the underlying storage, removing any previously
    * stored data.
    */
-  void format(NamespaceInfo ns);
+  void format(NamespaceInfo ns) throws IOException;
 
   /**
    * Begin writing to a new segment of the log stream, which starts at
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/JournalSet.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/JournalSet.java
index 7dc9b71f06..db64e63874 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/JournalSet.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/JournalSet.java
@@ -174,7 +174,7 @@ public boolean isRequired() {
   }
   
   @Override
-  public void format(NamespaceInfo nsInfo) {
+  public void format(NamespaceInfo nsInfo) throws IOException {
     // The iteration is done by FSEditLog itself
     throw new UnsupportedOperationException();
   }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestGenericJournalConf.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestGenericJournalConf.java
index 6096946b7e..a941ae424d 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestGenericJournalConf.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestGenericJournalConf.java
@@ -154,7 +154,7 @@ public DummyJournalManager(Configuration conf, URI u,
     }
     
     @Override
-    public void format(NamespaceInfo nsInfo) {
+    public void format(NamespaceInfo nsInfo) throws IOException {
       formatCalled = true;
     }